## Solución al problema número 190 de UVA - 190.

Cualquier duda no dudes en contactar.

``````#include <bits/stdc++.h>
#define INF 0x3f3f3f3f
#define EPS 10-8
#define PI acos(-1.0)
using namespace std;

struct point{
double x,y;
point(){x=y=0;}
point(double _x,double _y){x=_x,y=_y;}
bool operator <(point other) const{
if (fabs(x-other.x)>EPS)return x<other.x;
return y<other.y;
}
};

double dist(point p1, point p2) {                // Euclidean distance
return hypot(p1.x - p2.x, p1.y - p2.y); }           // return double

int circumCircle(point p1, point p2, point p3, point &ctr, double &r){
double a = p2.x - p1.x, b = p2.y - p1.y;
double c = p3.x - p1.x, d = p3.y - p1.y;
double e = a * (p1.x + p2.x) + b * (p1.y + p2.y);
double f = c * (p1.x + p3.x) + d * (p1.y + p3.y);
double g = 2.0 * (a * (p3.y - p2.y) - b * (p3.x - p2.x));
if (fabs(g) < EPS) return 0;

ctr.x = (d*e - b*f) / g;
ctr.y = (a*f - c*e) / g;
r = dist(p1, ctr);  // r = distance from center to 1 of the 3 points
return 1; }

int main()
{
double a,b,c,d,e,f;
while(scanf("%lf%lf%lf%lf%lf%lf",&a,&b,&c,&d,&e,&f)==6)
{
vector<point> V; V.push_back(point(a,b)); V.push_back(point(c,d)); V.push_back(point(e,f));
point o;
double r2;
circumCircle(V[0],V[1],V[2],o,r2);
r2 = (a-o.x)*(a-o.x)+(b-o.y)*(b-o.y);
char c1, c2, c3;
if(o.x >= 0)    c1 = '-';
else    c1 = '+';
if(o.y >= 0)    c2 = '-';
else    c2 = '+';
if(r2-o.x*o.x-o.y*o.y >= 0) c3 = '-';
else    c3 = '+';
printf("(x %c %.3lf)^2 + (y %c %.3lf)^2 = %.3lf^2\n", c1, fabs(o.x), c2, fabs(o.y), sqrt(r2));
printf("x^2 + y^2 %c %.3lfx %c %.3lfy %c %.3lf = 0\n\n", c1, fabs(2*o.x), c2, fabs(2*o.y), c3, fabs(r2-o.x*o.x-o.y*o.y));
}
return 0;
}
``````